1. Field of the Invention
The present invention relates to medical devices and more particularly, to needles for insertion of a bone cement mixture into a cavity of a damage bone.
2. Background
There is a clinical need to fill and stabilize damaged bones of patients, such as for example, filling defects in collapsed vertebrae of patients suffering from severe back pain caused by osteoporosis, metastatic tumors or back injuries. Currently, these defects are repaired using multi-component bone cements that are injected into the damaged bone where the mixture chemically reacts or cures to form a solid support structure. The most widely used bone cements are based on polymethylmethacrylate (PMMA) and hydroxyapatite.
One procedure that is typically used to fill defects in collapsed vertebrae is known as vertebroplasty. This procedure involves injecting bone cement directly into the fracture void through a minimally invasive cannula or needle. The bone cement may be radio-opaque and monitored via fluoroscopy. The cement may be pressurized by a syringe to cause the cement to fill the void. Once cured, the cement stabilizes the vertebra and reduces pain. Kyphoplasty is another similar procedure that may be used to inject bone cement into a fracture void. Typically, thicker bone cements are used with kyphoplasty than with vertebroplasty.
Although safe and effective, one issue with vertebroplasty and kyphoplasty is containment of the bone cement within the area of the vertebra having the defect. Cement may typically flow beyond the confines of the bone into other areas of the body. Typically, the bone cement has a high level of coherence such that the cement particles tend to adhere to other surrounding cement particles. Therefore, when an application cannula is withdrawn from the body, it will carry a trail of bone cement with it, which is typically cut near the skin surface.
To address the problem of cement containment within the bone fracture or void area, some practitioners have utilized fillable mesh bags or containers inside of the vertebra. However, upon filling, the expansion of such a bag or container can cause undesirable compaction on the surrounding fractured bone. Furthermore, the bag or container may still be permeable and release some of the bone cement into the surrounding body cavity. Another drawback of using mesh bags and/or containers is that they may add an expense to the procedure.
In view of the above and other defects known in the art, there remains a need for a bone cement delivery system that more adequately effects bone cement containment within the vertebra fracture, without adding significant costs to the procedure.